1. Technical Field
The present invention relates to a phase change memory apparatus, and more particularly, to a cell array structure of a phase change memory apparatus in which a row control cell serving as a local switch is embedded in a cell array area.
2. Related Art
Non-volatile memory apparatuses have characteristics that data stored therein is not lost even when power is interrupted. Accordingly, the non-volatile memory apparatuses are being extensively used for computers, mobile telecommunication systems, memory cards and the like.
A flash memory has been extensively used as a representative non-volatile memory apparatus. Besides, many types of non-volatile memory apparatus have been researched.
At the present time, as new non-volatile memory apparatuses capable of substituting for a flash memory, phase change memory apparatuses having random access characteristics of a DRAM are being actively developed.
According to a known art, a phase change memory apparatus includes a plurality of word lines, a plurality of bit lines crossing the plurality of word lines, and phase change memory cells arranged at the intersection points of the word lines and the bit lines.
The phase change memory cell may include a switching element coupled to a word line and a resistor coupled between the switching element and a bit line. The resistor may be formed of a phase change material of which a phase state is changeable depending on the temperature.
According to the known art, a first and second local switch units are installed at a side of the word line and a side of the bit line to select the word line and the bit line, respectively. The first local switch unit may include a MOS transistor coupled to the word line to respond a global address signal and a local address signal, and the second local switch unit may include the MOS transistor coupled to the bit line. The first and second local switch units may be arranged at a peripheral portion of a cell array.
Similarly to other memory apparatuses, there is a demand for a phase change memory apparatus with the high integration degree.
In this regard, various attempts are being made to reduce the cell area. For example, a diode of which a size is relatively smaller than that of a MOS transistor may be used as a switching element.